Detection of stable positive fixed charges in AlOx activated during annealing with in situ modulated PhotoLuminescence

In situ modulated photoluminescence study of the hydrogenation processes of tunnel oxide passivating contacts during plasma processes

“…During the hydrogenation processes in the MVS PECVD chamber (annealing, a‐SiN x :H deposition, NH 3 + H 2 plasma treatment), the minority carrier lifetime was monitored by an in situ MPL measurement setup mounted on the PECVD reactor, similar to the one described in a previous article. [ 9,16 ] The MPL characterization technique consists in shining a sample with a modulated laser intensity (excitation wavelength of 785 nm), which induces a modulation of the photoluminescence signal. By measuring the phase shift $$\phi $$ between this MPL signal and the excitation, the differential minority carrier lifetime $${\tau }_{{\rm{m}}}$$ can be determined through the equation given below [ 8 ] : $$$\phi =-\text{arctan}\unicode{x02007}(\omega {\tau }_{{\rm{m}}}),$$$where $$\omega $$ is the pulsation of the modulation of the laser in rad s −1 .…”

“…This study lead to the observation of the activation of positive fixed charges in Al 2 O 3 under the combined action of light and temperature. [9] In the present work, we investigate the possibility to use a simplified process flow for the fabrication of FPC samples, in a way close to the one proposed by Ingenito et al [10] As shown in Figure 1b and detailed in a previous communication, it consists in depositing sequentially a stack of silicon oxide (SiO x )/(p) nanocrystalline silicon (nc-Si:H)/a-SiN x :H and making a final firing step. [7] The tunnel SiO x layer provides chemical passivation to the surface of the wafer while allowing the transport of charge carriers by diffusion through pinholes or tunneling; the doped nc-Si:H layer has the role of a carrier-selective contact (conductivity, band bending).…”

“…This study lead to the observation of the activation of positive fixed charges in Al 2 O 3 under the combined action of light and temperature. [ 9 ]…”

Dielectric Front Passivation for Cu(In,Ga)Se2 Solar Cells: Status and Prospect

“…AlO x is also shown to have positive fixed charges when annealed at low temperature under light. [ 96 ] The deposition was at 150 °C in this case. Recently, a combined stack of PO x and AlO x revealed very high Q f between 10 12 and 10 13 e cm −2 and D it of 10 10 eV −1 cm −2 for as‐deposited layers.…”

Coupled Investigation of Contact Potential and Microstructure Evolution of Ultra-Thin AlOx for Crystalline Si Passivation

“…By taking advantage of the negative fixed charge density of AlO x itself, a passivation with surface recombination velocity (SRV) close to 10 cm/s has been achieved for p-type silicon [10]. Two main approaches have been developed to improve the passivation quality provided by AlO x including thermal annealing [11][12][13][14] and light-soaking [15][16][17].…”